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26 July/August 2014 global aquaculture advocate
production
About 50% of the operational cost of shrimp farming comes
from the aquafeed used. Feed management faces several huge
challenges. The shrimp feed sinks to pond bottoms, and feeding
adequacy cannot be visually monitored like in fish feeding. Feed
requirements change daily because of weather conditions and
water quality fluctuations.
Because of high density in a small volume of water, overfeed-
ing can quickly overload pond ecosystems, resulting in changes
in water quality and blooming of opportunistic microbiota, some
of which can be pathogenic. A better understanding of shrimp-
feeding management can avoid these problems and greatly
improve the bottom line.
Feed Quality
Not all feeds are created equal. Some feeds have better
digestibility, amino acid profiles and fatty acid profiles, and con-
tain sufficient immune stimulants. Selecting a consistently good-
quality feed will result in better average
daily growth, survival and feed conver-
sion, and thereby a better bottom line.
Tray-Based Feed Programing
Feeding guides developed by a feed
mill or individual farmer are based on
many trials and errors. In the first 25 to
30 days after stocking the postlarvae, the
feeding program is called blind feeding.
The daily feed volume given to the post-
larvae is deliberately programed to be
excessive. Much of the feed actually goes
to fertilize the pond water and enters the food web in the pond
ecosystem to end up mainly in the shrimp.
During this early stage, the postlarvae prefer natural feed. It
is not until 22 to 25 days after stocking that the juvenile shrimp
begin to take the commercial feed. Better-quality postlarvae
grow faster and begin to consume the feed earlier.
Several weeks after stocking, feed trays should be used to
monitor whether the feed amount is correct. This measure is
very important in intensive shrimp farming, because water qual-
ity can change abruptly, affected by weather conditions and feed
input. Through meticulously monitoring the feed trays, farmers
can detect a slowdown in feeding and adjust the feed amount,
thus enhancing shrimp health.
A 90-cm-wide by 120-cm-high water barrier positioned 15
to 30 cm upstream of the feed tray can ensure that no feed is
swept away by strong currents from aerators.
Water Quality
“To culture shrimp, one must first cultivate the water” is the
adage of many shrimp farmers in Asia. As shrimp are reared in a
small space with a small volume of water to maximize profit, the
shrimp excretions, uneaten feed and myriad opportunistic micro-
biota growing in it put tremendous strain on pond ecosystems.
Any inputs to the systems can greatly affect the water quality in
the small volume of pond water, as ponds are the “kitchens” as
well as the “toilets” of the shrimp. Shrimp farmers must always
take a holistic approach in managing ponds, keeping particularly
close watch on water quality and pond bottom hygiene.
Two of the major parameters that greatly influence shrimp
health are ammonia and hydrogen sulfide levels. The presence of
Feed Management Improves Profits
In Intensive White Shrimp Farming
Summary:
To ensure optimal water quality and clean pond bot-
toms at shrimp farms, choosing consistently good-
quality feed and close monitoring of feed trays sup-
ported by a proven feeding guide are recommended
practices to control the amount of feed applied to
ponds. The use of auto-feeders and biofloc technology,
as well as awareness of ponds’ carrying capacities, can
help shrimp farmers reduce feed costs, preserve capital
and maximize profit.
Poh Yong Thong
General Manager
Aqua Nutrition and Technical Service
P.T. Gold Coin Indonesia
Jalan Raya Bekasi km 28,
Desa Medan Satria
Bekasi 17132, Jawa Barat, Indonesia
yt.poh@goldcoin-id.com
Monitoring feed consumption via feed trays can indicate adjustments in feed
applications that maintain water quality and enhance shrimp health.
Copyright © 2014, Global Aquaculture Alliance. Do not reproduce without permission.
27
global aquaculture advocate July/August 2014
production
ammonia and hydrogen sulfide quickly escalates if there is over-
feeding. Ammonia, the by-product of protein degradation,
becomes noxious at pH higher than 8.5. Uneaten feed, shrimp
feces and dead microbiota become hydrogen sulfide in anaerobic
areas of pond bottoms. Hydrogen sulfide becomes toxic at a pH
of 6.5 and high temperature.
In intensive shrimp ponds with little water exchange or low
salinity, minerals such as magnesium, potassium and calcium can
become deficient due to direct uptake by the shrimp from the water.
These have to be periodically monitored to ensure optimal levels.
Bottom Quality, Sludge Removal
If feeding and water quality are not managed well, sunken
shrimp feces, uneaten feed and dead microbiota accumulate in
areas of stagnant water and become sludge. Pathogenic bacteria
grow profusely on the nutrient-rich sludge. When further shrimp
feed sinks onto these areas, it is contaminated by the pathogenic
bacteria and, if eaten by the shrimp, can result in disease.
Pond bottoms should be periodically monitored by farmers,
especially in semi-intensive systems where the number of aerators
used is low. The sludge areas can be marked by poles so they do not
receive feed. In intensive systems, the aerators normally sweep the
sludge into a stagnant area, where the sludge can be periodically dis-
charged. Some farmers even siphon the sludge periodically.
Auto-Feeders
The first use of auto-feeders in shrimp feeding was revolution-
ary. In the past, it was thought that feed must be spread evenly in
a pond so that all shrimp can feed optimally. But with auto-feed-
ers, the shrimp learn to come to the feeders when they are hungry.
An auto-feeder disseminates small quantities of feed intermit-
tently in minutes. Much of the feed is caught by the shrimp before
it sinks to the pond bottom. The feed does not have time to lose
its nutrients or pick up pathogenic bacteria from the pond bottom.
The author has tried using an auto-feeder, which spread feed
over an area of only 300 m2 in a pond of 8,000 m2. The growth,
survival and feed conversion achieved were better than when the
conventional method of spreading feed all over the pond was used.
Fasting
Fasting or interrupted feeding is a useful practice that not
only allows the scavenging Pacific white shrimp, Litopenaeus
vannamei, to clean up remaining organic matter on pond bot-
toms, but also allows the microbiota to catch up on consuming
the rich nutrients in the water. Both actions produce cleaner
pond bottoms and better water quality. It is a good practice to
Auto-feeders intermittently distribute small quantities of feed
that are caught by the shrimp before sinking to the pond bot-
tom and losing nutrients.
28 July/August 2014 global aquaculture advocate
carry out occasional weekly fasting for half a day to one day
when the shrimp are over 70 days old.
Applying reduced portions of feed after the sun sets is
another good practice, because most ponds experience low dis-
solved-oxygen concentrations in the absence of photosynthesis.
It is best to completely stop feeding for half a day or more if the
water temperature is well below 26° C, and the feed in trays is
not consumed.
Biofloc Technology
Biofloc technology is evolving to become a more and more
important aspect of aquaculture. In biofloc systems, strong aera-
tion keeps organic matter in perpetual suspension. Significant
amounts of microbiota “piggyback” on the organic matter, recy-
cling the rich nutrients available in the water.
What goes to waste in conventional aquaculture becomes
natural feed for the culture species, saving farmers significantly
on feed costs. However, only filter feeders such as L. vannamei
and tilapia can benefit from the natural feed in a biofloc system.
Carrying Capacity
Different ponds have different carrying capacities. For exam-
ple, new clean ponds can produce 1,000 kg shrimp/hp aeration.
However, ponds with old and dirty bottoms may produce only
400 kg/hp aeration.
Carrying capacity is defined by such factors as the level of
technology applied at a facility, the pond construction method
(e.g., earthen ponds, plastic-lined ponds or concrete ponds) and
amount of available aeration. Pond productivity can range 10-50
mt shrimp/ha.
When the carrying capacity of a pond is reached, problems
such as low dissolved-oxygen levels, slow growth, diseases and
mortality can arise. At these times, it is best to partially or totally
harvest the pond to ensure preservation of capital.
Temperature
The Pacific white shrimp is an aggressive feeder that eats
more at higher temperatures. In research, Dr. Chalor Limsuwan
of Kasetsart University in Thailand showed that shrimp feed
more at 32 than at 30° C. However, the growth of shrimp at
both temperatures was the same, so to save feed and money,
farmers should not feed excessively at temperatures above 30° C.
In biofloc systems, strong aera-
tion keeps organic matter
in perpetual suspension. Signifi-
cant amounts of microbiota “pig-
gyback” on the organic matter,
recycling the rich nutrients avail-
able in the water.
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